This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-367482, filed Nov. 30, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a resin-sealed semiconductor device having a leadless package structure.
2. Description of the Related Art
Leadless packaging of semiconductor devices has recently been advanced in order to meet the requirements for miniaturizing a portable terminal. A ceramic substrate employs an end-face through hole structure in which a through hole is formed in the end face of the substrate. The employment of the end-face through hole structure is common as a matter of solderability.
In order to manufacture semiconductor devices at low cost, plastic packaging for sealing a chip with resin is under consideration. Especially a resin printing method using liquid resin is predominant over a prior art transfer molding method. This is because an expensive mold is unnecessary and thus a reduction in cost can be accomplished.
However, if a substrate having an end-face through hole structure is sealed by the resin printing method, the following problem will occur. As shown in FIG. 12, resin 18 enters a through hole 51 from its opening portion and blocks an end-face electrode 13.
If an LGA (Land Grid Array) system not using an end-face through hole but using a normal via hole 61 is adopted as illustrated in FIGS. 13 to 15, it is the most suitable for a resin sealing process because the above problem does not occur. In the LGA system, however, an operator cannot visually check a degree of rising of solder after a motherboard is soldered. Such a solderability problem occurs.
A semiconductor device according to an aspect of the present invention comprises: a substrate; a semiconductor chip arranged on the substrate; a first electrode formed in the substrate and connected to the semiconductor chip; a concave portion provided on a side of the substrate, the concave portion extending from a back of the substrate and terminating in the substrate, and at least part of the first electrode being exposed to the concave portion; and a metal layer formed on the at least part of the first electrode.